OPERATION UNDER EMERGENCY CONDITIONS.

TM 9-4120-399-14

2-21. OPERATION UNDER EMERGENCY CONDITIONS.

a. NBC (nuclear, biological, chemical). This unit has provisions for connection to an

external NBC filtering source. The location of the NBC connection point is shown if Figure 2-

5. Should it be necessary to operate in conditions requiring use of NBC filtration equipment,

see specific instructions for your shelter or facility installation. For additional general NBC

information, refer to MIL-HDBK-116, Environmental Control of Small Shelters. The following

are general suggestions for operation in NBC hazards and do not apply if they conflict with

instructions for you shelter or facility installation.

(1) The fresh air damper should be closed, the opening should be covered with duct tape

(Appendix E, item 22) and sealed air tight.

(2) The conditioned air inlet louvers should be adjusted (partially or completely) closed

in conjunction with the NBC filter intake volume. This will cause a more positive pressure on

inside of shelter or enclosure and keep air from being drawn.

b. Power conservation. During periods when full 208 volt, 3 phase power is in critically

short supply, the air conditioner should not be turned off completely, but should be operated in

VENTILATE mode only.

Figure 2-5. Nuclear, Biological, and Chemical (NBC) Connection.